With the development of the communication technologies, mobile terminal such as cellphone has become a necessary electronic product in people's life, the consumers have more and more requirements on the functions thereof. In order to satisfy the consumers' requirements, the cellphone generally includes a metal back cover, the metal back cover includes a bottom, the bottom is provided with a gap, the gap extends along a width direction of the cellphone, so as to form an antenna.
However, in such a manner that the gap is provided at the bottom, in order to meet the antenna performance, the length of the gap needs to be relatively large, but the cellphone has a limited width. Therefore, the strength of the metal back cover is reduced, which affects the resistance against knocking.